Parts of San Rafael, a city just north of San Francisco, are sinking about half an inch a year. That may not sound like a big deal, but it means some areas, such as the canal district bordering the bay, have sunk by three feet, increasing the risk of flooding from rising sea levels.
It’s not just San Rafael. Cities around the world are under threat from rising sea levels, with 300 million people expected to be at risk of regular flooding by 2050. The cost of constructing seawalls to hold back water could exceed $400 billion in the United States alone.
A new startup is proposing an alternative: growing cities instead.
Terranova is developing a robot that injects a slurry of wood shavings into the ground and slowly lifts the land, reversing historic subsidence and hopefully preventing flooding in that area of the city.
“The Canal District is truly underwater,” Terranova co-founder and CEO Laurence Allen told TechCrunch. He said the city is working with flood consultants to find a solution.
“The answer was to build a $500 million to $900 million seawall, time and time again. If you’re from San Rafael, you know you can’t even afford that. There are about 60,000 people and, surprisingly for a city in Marin, a significant portion of them live in poverty.”
Terra Nova claims it can protect San Rafael and other similar cities at a fraction of the cost. For San Rafael, the startup estimated $92 million to lift 240 acres by four feet.
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The company recently raised $7 million in a seed round led by Congruent Ventures and Outlander, with participation from GoAhead Ventures, Gothams, and Ponderosa, TechCrunch has learned exclusively. The oversubscribed round values the company at $25.1 million.
Injecting materials underground to lift land is not new. Terranova’s pitch is that it has developed several new approaches to lower prices.
First of all, regarding materials, scrap wood is cheap and easy to obtain. The startup mixes it with undisclosed other ingredients into a slurry. The results are pumped from a 20-foot shipping container into a second cost-saving item, a robotic injection device. A tracked robotic unit moves autonomously around the work site and drills a well where wood slurry is dispensed to a depth of approximately 40 to 60 feet.
Allen said that as long as the slurry remains wet underground, the wood should not rot and the company could sell carbon credits to offset costs.
All of this is managed by software developed by Terranova. The company uses a combination of publicly available geographic information and data from cores drilled throughout California, primarily taken during well construction. This created a subsurface model that informed the injection pattern, which was determined by a genetic algorithm.
On the backend, city planners, contractors, and other stakeholders can use tools like SimCity to sculpt virtual landscapes.
Once the plan is complete, guide the robotic syringe and tell it where and how much to inject. Allen said a human operator remained on site as a safety measure. Once the robot is injected, the slurry takes about two hours to solidify, he added.
Terranova has been testing both the robot and software at the pilot site for more than a year, he said.
While some experts have questioned whether hardened wood slurry would worsen earthquake shocks, Allen said the most frequently mentioned alternatives also have risks. “We think it will help [with earthquakes] Against embankments and seawalls. ”
The company plans to make money by sharing project revenues with contractors. The company hopes the costs will be low enough to make the process attractive for a variety of land-raising projects beyond cities, such as restoring wetlands that are disappearing due to land subsidence and rising sea levels.
But given the urgency of rising water levels, cities are Terranova’s top priority. “I was born and raised in San Rafael,” Allen said. “I really want to save the city.”
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